Tumamoc Hill: A Desert Ecology Field Trip - Prof. Bonine, Lab Reports of Conservation biology

Download Tumamoc Hill: A Desert Ecology Field Trip - Prof. Bonine and more Lab Reports Conservation biology in PDF only on Docsity! ECOL 406L/506L Bonine, Epps Tumamoc Hill Field Trip 05 September 2008 Trip Goals: 1. Introduction to Conservation Biology Lab 2. Learn about the history, long-term research, and plant ecology of Tumamoc Hill 3. Visit an important historic site for Hohokam culture and desert research 4. Characterize the plant communities (and distributions) found at Tumamoc Hill 5. Learn about the various ways in which different plant species have adapted to the desert environment 6. Recognize and discuss human influences on the area (Santa Cruz River, livestock grazing, non- native plants, urbanization, habitat fragmentation, etc.) Introduction: Tumamoc Hill is approximately 4 km (2.5 mi.) west of downtown Tucson. The elevation at its base is 704 m (2,308 ft) above sea level. The summit is 948 m (3,108 ft). It comprises 352 ha (869 acres of land. According to the daily weather records kept since 1907, Tumamoc Hill’s average precipitation is 30cm (11.8 in) per year. Tumamoc is a modified Tohono O’odham word for “horned lizard.” Historic Events that occurred at Tumamoc Hill: ~1000 – 1450 A.D. Hohokam Indians inhabited Tumamoc Hill 1800’s Volcanic rock was removed from Tumamoc Hill for building foundations and rock walls in Tucson Early 1900’s Carnegie Institute built a desert laboratory to conduct ecological studies on the desert 1930’s During the depression, Carnegie Institute forced to shut down and offered the land to the U of A for $1. However, at the time, the U of A could not afford to keep the site running and turned down the offer. 1940 The U.S. Forest Service acquired the land with the understanding that it would be used for research purposes. 1960 Congress allowed the U of A to purchase the land for research and educational purposes. Today Current studies at Tumamoc Hill range from atmospheric pollution studies to population ecology. The Hohokam Indians were a group of relatively sedentary people who lived in southern AZ about 1000- 1400 A.D. There were two groups of Hohokam Indians: the Desert Hohokam and the River Hohokam. The Desert Hohokam lived along the Santa Cruz River. They are believed to have been the ancestors of the Tohono O’odham (Papagos) people. The River Hohokam lived along the Gila and Salt Rivers in greater concentrations than the Desert Hohokam. They are thought to have been the ancestors of the Pima people. The Hohokam farmed beans, squash, and corn in the flood plains and used some of the native desert plants such as mesquites, agaves, and saguaros for food and beverages. The Santa Cruz River was not an entrenched river like it is today, but a cienega (marsh-like) area. The Hohokam built irrigation ditches to bring water from the then permanent streams to their crops. They first lived in pit houses dug in the earth, but later built pueblo-like villages. They made trips to the Gulf of CA to collect shells and to trade with Indians from Sonora. Shells were used for jewelry, which they carved using an acid derived from fermented saguaro juice. The demise of the Hohokam Indians was probably due to climatic changes (evidence from tree rings), which made this area drier. When water became more scarce, even their small population exceeded the carrying capacity of the environment. Some of the artifacts left behind on Tumamoc Hill include: rock walls, rock circles, petroglyphs, and mortar holes. Three major plant communities found on Tumamoc Hill: 1. Palo-verde-saguaro community: foothill palo verde, saguaro, ocotillo, cholla cacti, brittle-bush. 2. Creosote bush community: creosote bush, triangle leaf bursage, desert zinnia 3. Dry wash (riparian) community: blue palo verde, mesquite, catclaw acacia Stops: A. Base of Tumamoc Hill Note composition of vegetative community, plant traits, soil characteristics, etc. B. Desert Lab Learn about the study plot (number 11) and discuss how plant diversity has changed over the past century. We will also discuss non-native grasses on Tumamoc Hill and the potential role of fire in the area. Travis Bean will join us for a discussion of buffel grass and other Tumamoc issues. The Tumamoc Library is a fantastic resource and archive. Enjoy. C. Summit Examine the artifacts left by the Hohokam Indians and the different vegetation types on the top (versus the bottom). Also discuss the surrounding landscape and plant diversity. In addition, we will discuss the Santa Cruz River and the Santa Cruz basin. Although portions of the River once experienced perennial surface flow, it is now ephemeral due to the lowering of the ground water level (dry ≈ 300 days/year). The Santa Cruz River bed is the primary location for ground water recharge; others are the Pantano Wash, the Tanque Verde Wash and the Rillito River, and some recharge takes place along the mountain fronts. Questions to keep in mind: 1. What makes each habitat unique? 2. Are the plants within each community distributed evenly or are they randomly distributed 3. Are there any differences in the vegetation at the base of the hill and at the top of the hill (sizes of individuals of same species, abundance, etc.)? 4. Are there any species at the top of the hill that were not at the bottom? Any role of aspect or slope? 5. At the top of the hill look at the different sides of the hill/other hills around. Do you notice any difference in the distribution of plants? If so, why? 6. Why do you think that these specific plant communities exist? 7. Can you note anything special about some of the classic Sonoran desert species like Saguaro, etc.?